we rehomed a orange wing Zon who was a bastard. he acted just like your grey. he would not step up and would bite piss out of you and would not stop he would tear into your hand like a hawk into a rabbit. I still have scars from him and that was 4 years ago. the only way we could move him around is to dangle a towel in front of him and let him climb on. that bird would bite hard, even through heavy leather gloves it felt like hulk hogan had a pair of pliers squeezing your finger. i finally just gave up trying, we were not in "his" flock and he had no intention of interacting with us.